Broca's Area and the Hierarchical Organization of Human Behavior Etienne Koechlin, Thomas Jubault  Neuron  Volume 50, Issue 6, Pages 963-974 (June 2006) DOI: 10.1016/j.neuron.2006.05.017 Copyright © 2006 Elsevier Inc. Terms and Conditions

Figure 1 Experimental Protocol The figure represents truncated series of trials in the simple (A) and superordinate (B) condition. Vertical arrows indicate the motor response that subjects made in each trial. In the simple condition (A), stimuli were a single square symbol, and subjects responded by pressing either the left (L), right (R), or both (LR) response buttons. In the superordinate condition (B), stimuli were pseudorandomly chosen letters A, B, or C (represented by the symbol X). In each trial, subjects performed a categorization task (represented above stimuli by c1, c2, c3), pressing either the left or right button (L/R) in response to each stimulus X. Horizontal arrows represent the transitions between the motor acts (A) and categorization tasks (B) comprising the simple and superordinate chunk, respectively. Colors of stimuli served as start and stop cues (green and red, respectively), triggering initiation and termination of chunk trials. Black color represents other randomly chosen colors (blue and yellow) that served as distractors. Left, endogenous termination, i.e., stop cues appeared at the end of learned sequences. Right, examples of exogenous termination, i.e., stop cues appeared before the end of learned sequences. See Experimental Procedures for additional information. Neuron 2006 50, 963-974DOI: (10.1016/j.neuron.2006.05.017) Copyright © 2006 Elsevier Inc. Terms and Conditions

Figure 2 Behavioral Results Reaction times to stimuli (mean ± SEM across subjects averaged over correct responses) in chunk trials. Init, initiation trials. Inter, intermediate trials occurring after start and before stop cues. Term, termination trials. Exo, exogenous; Endo, endogenous. Subject's error rates were lower than 8% in every trial type. Trials including errors were factored out in all analyses. Neuron 2006 50, 963-974DOI: (10.1016/j.neuron.2006.05.017) Copyright © 2006 Elsevier Inc. Terms and Conditions

Figure 3 Topography of Lateral Frontal Activations Green: regions activated in transitions between single motor acts. Yellow: regions jointly activated in initiation/termination of simple chunks and in transitions between simple chunks. White: regions activated in initiation/termination of simple chunks only. Orange: regions activated in transitions between simple chunks only. Red, regions activated in initiation/termination of superordinate chunks only. Activations are superimposed on anatomical axial slices averaged across subjects (neurological convention) and indexed by the vertical Talairach coordinate (z). Only lateral frontal activations are shown. Neuron 2006 50, 963-974DOI: (10.1016/j.neuron.2006.05.017) Copyright © 2006 Elsevier Inc. Terms and Conditions

Figure 4 Time Courses of Lateral Frontal Activations Reconstruction of event-related magnetic resonance (MR) signal changes associated with each trial type in anterior (top), posterior (middle) BCA, and lateral premotor (bottom) regions averaged over both hemispheres and subjects (error bars are standard errors across subjects). Solid lines: superordinate condition. Dashed lines: simple condition. Left, initiation trials. Middle, intermediate trials and baseline (no symbol) trials. Right, termination trials. x axis origins are stimulus onsets. For each trial type, data points are adjusted and peristimulus MR signals averaged over time bins of 2 s and obtained after subtracting the estimated contribution of other events based on parameter estimates of the multiple linear regression model. Data points are positioned on the x axis at the center of time bins (i.e., at 1 s, 3 s, 5 s, etc.). y axis origins are the averaged event-related MR signal in motor baseline trials (middle and bottom panels) and chunk baseline trials (top panel). Neuron 2006 50, 963-974DOI: (10.1016/j.neuron.2006.05.017) Copyright © 2006 Elsevier Inc. Terms and Conditions

Figure 5 Topography of Insular and Pre-SMA Activations The color code is the same as in Figure 3. Yellow: regions jointly activated in initiation/termination of simple chunks and in transitions between simple chunks. White: regions activated in initiation/termination of simple chunks only. Orange: regions activated in transitions between simple chunks only. Activations are superimposed on anatomical axial slices averaged across subjects (neurological convention) and indexed by the vertical Talairach coordinate (z). Talairach coordinates of activation peaks are provided in Table 1. Neuron 2006 50, 963-974DOI: (10.1016/j.neuron.2006.05.017) Copyright © 2006 Elsevier Inc. Terms and Conditions

Figure 6 Phasic and Sustained Activations in the Insula and Pre-SMA (A and C) Graphs show reconstruction of event-related magnetic resonance (MR) signals associated with each trial type. Solid lines: superordinate condition. Dashed lines: simple condition. Left, initiation trials. Middle, intermediate trials and baseline (no symbol) trials. Right, termination trials. y axis origins are the averaged event-related MR signal in motor baseline trials. (B and D) Graphs show reconstruction of epoch-related magnetic resonance (MR) signals during simple (square, dashed lines) and superordinate (circle, solid lines) conditions. In all graphs, data points are MR signals averaged over both hemispheres and subjects (error bars indicate standard errors across subjects). x axis origins are stimulus onsets. Data points are adjusted and peristimulus MR signals averaged over time bins of 2 s and obtained after subtracting the estimated contribution of other events based on parameter estimates of the multiple linear regression model. Data points are positioned on the x axis at the center of time bins (i.e., at 1 s, 3 s, 5 s, etc.). Neuron 2006 50, 963-974DOI: (10.1016/j.neuron.2006.05.017) Copyright © 2006 Elsevier Inc. Terms and Conditions

Figure 7 The Proposed Model of Hierarchical Control in BCA Regions Left, functional organization of BCA regions. Right, schematic diagram representing how this functional organization is involved in hierarchical control based on processing start (S) and end (E) states of functional segments forming the hierarchical structure of action plans. Neuron 2006 50, 963-974DOI: (10.1016/j.neuron.2006.05.017) Copyright © 2006 Elsevier Inc. Terms and Conditions